Cutting or sawing machine

ABSTRACT

A preferred embodiment of a hand-operated flush cutting machine includes a front section with a first and a second disc shaped cutter blade which are rotary about an axis of rotation and mounted in the front end of an elongated tool carrier having the substantial shape of a flat bar. The tool carrier is mounted to a rear section of the machine. The rear section is provided with a number of components, including a motor for driving the cutter blades via a power transmission as well as handles and a control for operating the machine. The first, right hand side cutter blade has a first side, which does not face the second cutter blade. The first side defines a first plane which does not intersect any component in the front or rear sections.

TECHNICAL FIELD

The present invention relates to a lightweight flush-cutting or sawingmachine which is designed to be operated hand-held. In spite of its lowweight and small size, however, the machine is also useful for cuttingeven thick concrete walls, roofs, floorings or pillars as well as forperforming special tasks, including cutting narrow grooves in concretefloors or walls, flush against walls and floors, respectively. Themachine of the invention therefore is a versatile utensil intended inthe first place for the construction industry.

BACKGROUND OF THE INVENTION

Flush cut sawing is conventionally performed by means of heavy machines,which typically are carried by wheeled vehicles or by carriers on railsor the like, which make them cumbersome to install and often also tohandle. Another drawback, besides that they typically are expensive, isthat they are special-type machines, which have only a restricted fieldof use. However, also more simple and less expensive, light, hand-heldand hand-operated flush-cutting machines are known in the art, such asangle grinding machines. Such machines, on the other hand can cut onlyto quite small depths, and are not very efficient cutters either.Besides, they have typically drawbacks from an ergonomic point of view.Therefore, for these and other reasons, there exists a need for flushcut sawing or cutting machines which do not have the mentioned or otherserious drawbacks or shortcomings.

BRIEF DISCLOSURE OF THE INVENTION

It is the objective of the invention to address the above mentionedproblems. More specifically, it is a main objective of the invention toprovide a cutting or sawing machine which

-   -   has excellent flush cut properties,    -   has so low weight that it can be hand-held and operated by an        operator single-handed, and    -   satisfies high requirements from an ergonomic point of view,        including small risk for kick backs or other behaviours of a        hazardous nature.

It is also a purpose of the invention to provide a machine which can beused not only for flush-cutting but more or less as a universal cuttingmachine on a building site, including for cutting even thick walls,floors, ceilings or pillars of concrete, bricks or other buildingmaterials. A special, and probably unique task which the machine shouldbe able to perform readily is to cut narrow grooves in floors, walls orceilings, flush against walls, ceilings or floors.

These and other objectives can be achieved therein that the machine ischaracterized by what is stated in the independent patent claim. Otherfeatures and objectives are apparent from the dependent claims and fromthe following detailed description of a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF DRAWINGS

In the following description of a preferred embodiment of the invention,reference will be made to the accompanying drawings, in which

FIG. 1 is a perspective view of the machine according to the preferredembodiment of the invention showing the top, left hand side and thefront as viewed obliquely from above, front and left,

FIG. 2 shows the opposite side of the machine obliquely from the front,

FIG. 3 is a rear end view of the machine,

FIG. 4 is a top view of the machine provided with two circular cuttingtools and prepared for non-flush-cutting,

FIG. 5 shows the same machine as in FIG. 4 but prepared forflush-cutting,

FIG. 6 is a view along the lines VI-VI in FIG. 5, schematically showingthe front parts of the tools and the tool carrier of the machineprovided with two circular cutting tools,

FIG. 7 is a corresponding view of a machine provided with only onecircular cutting tool,

FIG. 8 shows parts of a power transmission, a gear housing and a rearportion of a tool carrier in cross section in a plane defined by theaxes of rotation of a driving motor and rear driving pulley,

FIG. 9 is an exploded view illustrating a bar included in the toolcarrier, various members related to the attachment of the tool carrierto the rear section of the machine, means for tensioning a V-belt, andparts of the power transmission as well as the housing thereof shown inFIG. 8, and

FIG. 10 is an exploded view illustrating guard components included in amid section of the machine.

DESCRIPTION OF A PREFERRED EMBODIMENT

With reference first to FIG. 1-FIG. 4, a machine of the invention isgenerally designated 1. Its main parts are an elongated rear section 2,an elongated front section 3, and a mid section 4 of short length. Therear section in turn consists of a rear main portion 5 and a frontportion 6 of shorter length. The basic design of the front section 3 isknown per se through the International Publication WO 2006/101423, thedisclosure of which is herewith incorporated in the present descriptionby reference, and includes an elongated tool carrier 11, two circular,rotary cutter blades 7 and 8, one on each side of the tool carrier 11,and upper and lower front blade guards 9, 10. A plane of symmetry of thefront section 3, perpendicular to an axis of rotation 26 of the cutterblades 7 and 8, is designated 14, FIG. 5. The mid section 4 includes ashield 12 protecting the rear section 2 of the machine. A front handle13 is provided in the rear end of said front portion 6 of the rearsection 2. A rear blade guard 15 is pivotally connected to the shield 12such that it can be folded up against the shield in the mid section 4and is also provided displaceable in lateral directions allowingflush-cutting as well as normal, non-flush-cutting operations of themachine, as will be explained more in detail in the following.

In the rear section, an elongated rear handle is designated 16. Anelectric motor 17, schematically shown in FIG. 8 and indicated by dashedlines in FIG. 4, is accommodated in a motor housing 18 to the rear ofsaid front portion 6. A control device 25 for operating the motor 17 isprovided in a manner known per se in connection to the rear handle 16. Anot shown stator shell of the motor 17 has a substantiallycircular-cylindrical outer shape and is attached to the motor housing18, substantially filling the space that is available inside the roundedright and left hand side walls 22, 23 of the motor housing 18 in therear main portion 5 of the rear section 2. The axis of rotation 19 ofthe motor 17 and of a motor shaft 24 extends in the longitudinaldirection of the machine 1 and coincides with a central plane 20 ofsymmetry of the rear main portion 5 of the machine 1, which means thatthe rear main portion 5, which includes the driving motor 17 is wellbalanced. Said plane 20 is a vertical plane when the machine 1 hasadopted the position shown e.g. in FIG. 3, which hereinafter bydefinition is referred to as the normal position of the machine,although the machine can be operated in any conceivable position. Anelectric cable 34 is connected to the rear end of the machine 1.

As is clearly shown in the drawings, the rear section 2 has a veryslender design, which is made possible due to the shape and provision ofthe motor 17. The slender design, although known per se in the art, isof significant importance for the achievement of the desired ergonomicfeatures of the machine 1, because it makes a short distance ds from thecentral plane of symmetry 20 of the rear main portion 5 of the rearsection 2 to the plane of symmetry 14 of the front section 3 and also ashort distance df to a flush-cutting plane 21 of the machine 1 possible,FIG. 3. The good balance of the machine 1 also promotes a safe cutting.

In the front section 3, the two coaxial cutter blades 7 and 8, whichboth are flush-cutting type of cutter blades, are rotary about an axisof rotation 26. Each cutter blade 7, 8 consists of a flat blade body 7Aand 8A, respectfully, made of steel and peripheral diamond segments 7Band 8B which are the working parts of the cutter blades. The outer side,i.e. the side opposite the side facing the tool carrier 11, of the righthand side cutter blade 7, more specifically the outer side of the bladebody 7A, defines a plane, which may be referred to as a first plane 21.The diamond segments 7B and 8B are slightly thicker than the bladebodies 7A and 8A. They therefore protrude slightly beyond the planes ofthe blade body sides, which means that e.g. the outer sides of thediamond segments 7B on the right hand side cutter blade defines an outerplane at a very short distance from said first plane 21. This isimportant for an efficient operation of the cutter blade, and it alsogives a certain play which the operator can take advantage of whenperforming flush cut operations, but in other respects the differencebetween the two planes, which amounts to only a few tenths of amillimeter, can be neglected. The said first plane 21 therefore withgood accuracy corresponds to said flush-cutting plane 21.

The flush-cutting plane 21 also coincides with a plane of the outersurface of a support member 32 which forms part of the front handle 13,connecting a top section 33 of the front handle 13 with the main body ofthe rear section 2 of the machine 1. It is also in plane with wallsection 53, right hand side wall of tool carrier 11, and right hand sidewall 22 of rear main portion 5. When cutting e.g. into a wall flushagainst the floor in order to establish a door opening without anythreshold, or cutting a pillar without leaving any rest, not even a veryshort stump above the floor surface, the operator may contact saidsupport member 32, and the other of said members in plane with the saidsupport member, lightly against the floor, which promotes a correct andsafe flush cutting. The support member 32 in other words aids theoperator for the achievement of a desired flush cut.

As mentioned in the foregoing, the basic design of the front section 3which is employed in the machine 1 belongs to prior art and does notform part of the present invention per se. Therefore it will not bedescribed here in any detail. However, it might be stated that the toolcarrier 11 includes a bar 28 of solid steel, the rear end of which isshown in FIG. 8. The bar is covered by panels 29, 30 made of thin steelsheet and in its front end the bar is provided with two driving wheelhalves 201, one on each side of the bar, which are connected with oneanother by a shaft, which is journalled in the bar 28, such that thedriving wheel halves in combination form a front driving wheel for therotation of the cutter blades 7 and 8, which are secured to the drivingwheel halves 201. Both cutter blades are flush-cutting blades, whichmeans that no part of the cutter blades protrudes beyond the side planesdefined by the edge segments 7A and 8B. A V-belt 31 is employed, poweredby the motor 17, for the rotation of the front driving wheel. When themachine 1 shall be used for cutting operations to depths which maycorrespond up to the total length of the front section 3 of the machine1, the machine is conveniently provided with both the two cutter blades7 and 8. If on the other hand, the required cutting depth is fairlysmall and amounts to not more than the radial distance from the frontedge of the cutter blade to the front tip of the tool carrier, merely asingle cutter blade may suffice. If it is the question of a flush cut tosaid small depth, the right hand cutter blade 7 is employed. On theopposite side of the tool carrier, the left hand cutter blade 8 in thatcase may be replaced by a driving wheel half without cutter blade orwith a small blade which does not extend beyond the front tip of thetool carrier. In this connection, reference is made to the EuropeanPatent No 1 252 956, FIG. 8, and related parts of the patentdescription, the disclosure of which herewith also is incorporated inthe present application by reference.

In a flush cut sawing machine it is not possible to achieve completesymmetry, without sacrificing other important features since theflush-cutting tool necessarily has to be laterally displaced relative tothe rest of the machine. When designing the machine of the presentinvention it has, however, been an ambition to minimize thedisplacement, which may be referred to as the measure df mentioned inthe foregoing. This, on the other hand, causes new design problems,because the tool carrier 11 will have to be safely attached to the rearsection of the machine within a region of the front portion 6 having adesired small extension in the lateral direction, in which region alsothe front handle 13 shall be attached, and a power transmission betweenthe motor shaft 24 as well as devices for tensioning the V-belt shall beaccommodated. How this complex of problems has been solved shall now beexplained with reference to FIG. 8 and FIG. 9.

With reference first to FIG. 8, a right angular gearing 35 isaccommodated in a gear housing 36, which is attached to the motorhousing. The gearing 35 consists of two cooperating bevel gear wheelsmounted on their respective shafts, namely a first bevel gear wheel 37on the motor shaft 24 and a second bevel gear wheel 38 on an outputshaft 39. The axis of rotation 19 of the motor 17 and of the motor shaft24 forms right angle to the axis of rotation 40 of the output shaft 39.The two axes 19 and 40 are in plane with one another and also with theaxis of rotation 26 of the cutter blades 7, 8. The motor shaft 24 ismounted in a first bearing 41 in a gear housing wall 42 facing the motor17, whereas an inner end of the output shaft 39 is mounted in a secondbearing 43 in a protrusion 44 of the wall 48 of the gear housing 36 onthe left hand side of said housing, and an outer end of the output shaftis mounted in a third bearing 45. Said third bearing 45 in turn ismounted in an output side cover 46 and secured in said cover by means ofa flange 47. A driving pulley 49 for the V-belt 31 is attached to theouter end of the output shaft 40 by means of a screw 54 via a spacingsleeve 50.

The exterior of the gearing housing 36, including the walls 42 and 48,and the shape of the protrusion 44, are shown in FIG. 9, which alsoshows the distribution of a number of holes 51 in the wall 42 for theventilation of the interior of the motor housing 18. A number ofventilation holes 52 are also provided in a right hand side wall section53 of the gear housing 36.

The driving pulley 49 and a section of the V-belt 31 are covered by apanel made of sheet material, in this text denominated rear belt guard56. Said rear belt guard 56 forms part of the front section 3, themid-section 4, as well as of the rear section 2 of the machine 1 andforms an interconnection between those main parts of the machine. Afront section 57 of the rear belt guard has a first, front portion 57Awhich is flat, having an outer surface coinciding with the plane of theouter side of the front part of the tool carrier 11, and a secondportion having a cavity 57B, FIGS. 2, 8, and 9, at the rear of the firstportion 57A. A rear section 58 of the belt guard 56 as a whole has amore complex shape and is connected to the gear housing 36 by means ofscrews 59 extending through two small, circular holes 60 in the rearbelt guard 56 and also through two elongated holes 61 in a bar bracket62.

The purpose of the bar bracket 62 is to form a connection between thebar 28, forming the central part of the tool carrier 11, and the gearhousing 36, allowing the bar bracket 62 and the bar 28 to be moved inthe longitudinal direction of the tool carrier 11 relative to the gearhousing 36 and to the driving pulley 49. For the latter purpose, the twoholes 61 have an elongated shape and are provided in each of two fingers63 of the fork-like bracket 62. An open space between the finger-likeprotrusions 63 of bracket 62 is designated 64. The rear end of the bar28 has four holes 65. In a front, laterally protruding part 66 of thebracket 62, four matching threaded holes 67 are provided for screwjoining the bar 28 to the outer side of the bracket 62.

A V-belt tensioning eccentric 70 made of a flat piece of steel sheet isprovided in the above mentioned cavity 57B in the front section 57 ofthe rear belt guard 56. The eccentric 70 is secured in the cavity bymeans of a screw 71, FIG. 2, which extends through a hole 72 in theeccentric 70 and through an elongated slot 73 in the bottom of cavity57B and through a hole 74 in the protruding part 66 of the bar bracket62 at the rear of the rear end of the bar 28. A nut, not shown, isaccommodated in a seat 75 securing the screw 71 and hence the eccentric70 to the bar bracket 62. Further, a device, denominated brackettensioner 76 is secured by screws to the gear housing 36. A protrudingnose portion 77 of the bracket tensioner extends through the slot 73into the cavity 57B. In the bottom of the cavity 57B two different screwdrive recesses are provided, one for a conventional flat tip screwdriver and another one for a Torx screw driver. Normally, the barbracket 62 is tightly secured by nuts against the gear housing 36 incooperation with two screws 59, which extend through the holes 60 in thepanel 56 and further through the elongated holes 61 in the bracket 62.If the nuts are eased, the bar bracket 62 can be displaced in thelongitudinal direction by means of a screw driver, fitting in any of thescrew drive recesses in the eccentric 70. By means of the fitting screwdriver, the eccentric 70 is turned about the screw 71, urging the camprofile of the eccentric against the nose portion 77 of the brackettensioner 76, which works as a counterstay, such that the eccentric 70will force the bar bracket and hence the bar 28 to move in thelongitudinal direction, tensioning the V-belt 31. Upon tensioning theV-belt, the bar bracket 62 can be refastened by said nuts in the newposition in the elongated holes 61. It should be understood that theentire operation for tensioning the V-belt and securing the bar in a newposition can be carried out from outside by means of the eccentric 70and the nuts.

The shield 12 with the rear blade guard 15 and the front handle 13,which supports the shield, form an integrated unit from a functionalpoint of view. The shield 12 and the rear blade guard 15, which ispivotally connected to the shield 12, together form the mid section 4 ofthe machine 1. The mid section 4 has quite a small extension when theblade guard is in upraised position, representing only about 3-4% of thetotal length of the machine 1. The front handle 13 is secured to thegear housing 36 via said support member 32 on the right hand side of themachine. A vertical left hand side section 79 of the front handle 13 ismounted via a connection piece 81, which is turned inwards, connected tothe gear housing 36 on the bottom side thereof. The shield 12 basicallyhas the shape of a rectangle with rounded top and bottom left corners 82and 83, respectively, and is made of a strong plastic material. Astraight top edge 84 and a straight left hand side edge 85, respective,extend slightly above and beyond the top and left hand side sections 33and 79 of the front handle 13, respectively, while a bottom portion 86with a straight bottom edge 87, on which there are provided two feet 88,form a support, allowing the machine 1 to rest on a horizontal ground.The right hand side of the shield has a recess 90, FIG. 10,accommodating the rearmost end of the tool carrier 11, FIG. 1 and FIG.8, but sections 89A and 89B of the right hand side edge above and belowthe recess 90 are straight and extend close to the flush-cutting plane21.

The shield 12 is connected to the front handle 13 through a broad wingmember 91 forming an additional guard for the operator holding themachine with his left hand about the front handle 13. The wing member 91is connected to the front handle 13 close to where the support member 32is connected to the top portion 33 of the handle. The shield 12 isfurther connected to the front handle 13 through a strut 92 providedbetween the shield and the connection piece 81 in a lower part of theshield. But the shield 12 is also connected directly to the gear housing36 by screws 93, FIG. 1, which extend into threaded screw holes 93A in afront portion 94 of the gear housing 36, which rests in a shallow cavity95 on the rear side of the shield 12.

The rear blade guard 15 is made up of a number of separate components,which are connected to one another, including a flexible section 102 anda flexible top section 98, both flexible sections are made of a flexiblepolymeric material and are connected to a stiffer main section 99 whichhas sides which are aligned with the sides of the flexible top section98, the main section 99 comprising left hand portion 101 which extendsalong the left hand side of the tool carrier 11.

According to an aspect of the invention, the rear blade guard 15 is notonly pivotally connected to the lower portion 87 of the shield 12 butcan also be displaced sideways relative to the shield 12 to makeflush-cutting possible. For that purpose, all the various members areprovided, which are shown in a lower, left part of FIG. 10. Thesemembers include a rocker 106, a seat 107, and a retainer 108. Further arecess, which can accommodate the seat 107 and the retainer 108 isprovided in the front of the lower portion of the shield 12 and, on theopposite rear side, a hole 117, 118 is provided in each side wall of aprotruding portion 110 corresponding to the recess on the front side,such that the rocker 106 can enter said recess from the rear side of theshield 12, be mounted in said holes 117, 118 and slide sideways in theholes. A lever on the rocker 106 is designated 111. Other membersincluded in the assembly are a sleeve 112, two O-rings 113, and atorsion spring 114, which shall be accommodated in a through horizontalboring 115 in the lower end of the main section 99 of the rear bladeguard 15. A screw and a nut are designated 119 and 120, respectively.

In the assembly consisting of the above described members, the sleeve112, washers 113 and torsion spring 114 are inserted into the boring 115in the blade guard 99. The retainer 108 is provided with two ears 121,which are entered through an elongated, horizontal slot 122 in the frontwall of the seat 107. The web portion 123 of the retainer 108, however,is so broad that it can not pass through and is therefore retained onthe rear side of the retainer 108. Now, the lower tip portion of theblade guard 99, which contains said boring 115 accommodating saidmembers 112, 113 and 114, is entered between the two ears 121 of theretainer 108, which protrude beyond the front side of the seat 107.Next, the screw 119 is entered from the left with reference to FIG. 10through a hole 125 in the first ear 121 and further on through theassembly, including the sleeve 112 and the spring 114, which istightened in a mode per se, inside the bottom tip portion of blade guard99, and finally through a hole 126 in the opposite ear 121. The nut 120is mounted on the protruding end of screw 119, wherein the blade guard99 has been pivotally secured to the seat 107. It can also be displacedsideways relative to the seat 107, because the seat 107 and the slot 122in the seat are longer than the total length of the retainer 108,screw-head and nut 120. Now, ears 127 of seat 107 are moved into therecess 198, whereupon the seat 107 with the blade guard 99 securedthereto, is fastened to the shield 12 by means of screws. Finally, therocker 106 is entered into the seat 107, through the first hole 117 onthe rear side of the shield 12, then via recesses 128 in the ears 127 ofseat 107 and finally through the opposite hole 118. A protruding centralsection 130 of the rocker 106 has a length corresponding to the distancebetween the ears 121 of the retainer 108 and is accommodated in thespace defined sideways by the said two ears 121, rearwards by the webportion 123 and in the front direction by the tip portion of the bladeguard section 99, which closes the slot 122. By means of the lever 111,the rocker 106 can be moved forth and back in the recess 198 between theears 127 of the seat, said protruding section 130 of the rocker 106causing the rear blade guard 15 to join the rocker lever in thedisplacement movement. The length of the displacement movementscorresponds to the width of the second, finger-shaped portion 104 of therear blade guard 15. The rocker 106 is released from and locked inlocking end positions by turning the rocker by means of the lever 111.

As has been mentioned already in the preamble of this description, themachine 1 of the present invention is a versatile tool which can be usedfor standard cutting operations particularly in the constructionindustry but also for special tasks, in the first place forflush-cutting operations. For standard cutting operations, the machine 1is normally provided with two cutter blades 7, 8 and with the rear bladeguard 15 arranged in the mode shown in all the drawings except FIG. 5.It is, however, also possible to use only one cutter blade 7, as isindicated in FIG. 7, at least when the cutting depth is comparativelysmall. Also, for flush-cutting operations, one or two cutter blades maybe employed, but if the cutting depth is large, which it normally is inthe construction industry, the machine 1 is provided with its two cutterblades 7, 8. For adapting the machine to flush-cutting, the rear bladeguard 15 is moved to the left upon unlocking the rocker lever 106 bymeans of the lever 111. Then the rocker lever 106 is locked again in thenew position. As is shown in FIG. 5, the rear blade guard 15 now doesnot hinder the machine from working flush against e.g. a wall or a floorfor performing flush-cutting. For both kinds of operation, standardnon-cutting operations as well as flush-cutting operations, the guardagainst the cutter blades 7, 8 is very good, due to the front bladeguards 9, 10 in combination with the rear blade guard 15, whether therear blade guard is in its normal position or moved aside. In the lattercase, also the object against which the machine operates flush, e.g. awall or a floor, plays the role as a guard against the cutter blades andit also forms a barrier against spatter in combination with the shield12, which hinders saw dust and the like from hitting the operator orhitting the rear parts of the machine 1.

It is also possible to make narrow grooves e.g. in a floor flush againsta wall, or vice versa, by means of the machine of the invention,provided with its two cutter blades 7, 8. Such grooves can be used foraccommodating electrical or other conduits, and/or for the accommodationof borders, sealings and the like.

It should also be understood that the invention can be modified withinthe frame of the appending claims. For example, the rear tool guard 15can be designed in other modes for allowing non-flush as well asflush-cutting operations without jeopardising its guard efficiency. Forexample, the right hand part of the guard may consist of a member whichcan be dismounted for flush-cutting operations, or be connected to theleft hand part of the guard via a hinge, such that it can be foldedaside or it may consist of a flexible material allowing it to be foldedaside.

The invention claimed is:
 1. A hand-held, hand-operated, cutting or sawing machine comprising: a front section and a rear section; the front section includes at least a first, disc-shaped cutter blade, which is rotary about an axis of rotation, said first cutter blade having a peripheral edge portion which is the working part of the first cutter blade, said first cutter blade having a first side defining a first plane, and a second side defining a second plane, said first cutter blade is rotatably mounted in a front end of an elongated tool carrier, said elongated tool carrier having a substantial shape of a flat bar having two opposite side walls which are parallel with said first and second sides of said first cutter blade, said front end further comprising an upper front blade guard and a lower front blade guard; a rear end of the elongated tool carrier is connected to said rear section of the machine at a location rearward of said first cutter blade, said first cutter blade is provided on a first side of a center plane of the front section, said second side of said first cutter blade facing the tool carrier, said rear section includes a motor that drives the first cutter blade via a power transmission, and said rear section further includes a housing, handles, and a control device trigger for operating the machine, said first plane does not intersect any component, besides the first cutter blade, included in said front or rear sections, a rear tool guard having a flush-cutting mode and a non-flush-cutting mode, and in the flush-cutting mode said first plane does not intersect the rear tool guard, but does intersect the rear tool guard in the non-flush-cutting mode, wherein the rear tool guard is connected to a mid-section of the machine, and said rear tool guard includes a lateral part which optionally can be maintained intersected by said first plane or be withdrawn from the first plane and from the region outside of the first plane, and wherein a lower end of the rear tool guard is pivotally connected to a bottom portion of a shield, and is displaceable in lateral directions by a rocker and a rocker lever on a rear side of said bottom portion of the shield.
 2. Machine according to claim 1, wherein the rear tool guard is arranged to be displaced in said lateral directions sideways between the flush-cutting mode and the non-flush-cutting mode.
 3. Machine according to claim 1, wherein a drive wheel half for rotatably supporting an optional, second disc-shaped, rotary cutter blade is provided on a second side of the center plane of the front section, said drive wheel half is provided with means for detachably securing said second disc-shaped cutter blade to said drive wheel half.
 4. Machine according to claim 1, wherein the length of said rear section and the length of said front section are approximately equal.
 5. Machine according to claim 1, wherein said handles include an elongated, longitudinal, rear handle near said first plane in a rear end of the machine's rear section and a transversal front handle near a front end of said rear section.
 6. Machine according to claim 5, wherein a center plane of said elongated rear handle is parallel to said first plane and the center plane of said elongated rear handle is located at a lateral distance from the center plane of the front section, the center plane of the front section being defined by a longitudinal center of the elongated tool carrier, and parallel to the first plane and the second plane, a rear end of the rear handle is located at a longitudinal distance from said axis of rotation of said first cutter blade, and wherein the ratio between said lateral distance and said longitudinal distance amounts to less than 1/10.
 7. Machine according to claim 6, wherein the ratio is less than 1/20.
 8. Machine according to claim 1, wherein said rear section includes at least one side member with a thickness extending in a lateral direction to said first plane.
 9. Machine according to claim 8, wherein said at least one side member has at least one flat side surface, the plane of which coincides with said first plane.
 10. Machine according to claim 1, wherein the power transmission includes a motor shaft, a driving belt, a driving pulley that drives the driving belt, an output shaft mounted to said driving pulley, and an angular gearing that connects said motor shaft to said output shaft, and wherein the axes of rotation of the motor shaft, the output shaft and the first cutter define a common plane.
 11. Machine according to claim 10, wherein the motor shaft extends in a longitudinal direction of the machine, and the angular gearing is a right-angular gearing.
 12. Machine according to claim 10, wherein a driving wheel half that supports the first cutter blade is provided at the front end of the elongated tool carrier, and wherein a driving belt tensioner is provided for tensioning the driving belt by moving the elongated tool carrier forwards, said belt tensioner including an eccentric provided rotary in a cavity on a right-hand, flush-cutting side of the machine.
 13. Machine according to claim 1, wherein said housing has a first side on the same side of said center plane of the front section as said first plane closely to said first plane, said first side of the housing facing said first plane, and said housing has a second side on the opposite side of said center plane.
 14. Machine according to claim 1, wherein the shield hinders sawdust or cuttings from hitting the rear section, the shield is provided in a mid-section between the front section and the rear section and is not intersected by said first plane.
 15. Machine according to claim 14, wherein the mid-section has a length in the longitudinal direction which is less than 5% of the total length of the machine.
 16. Machine according to claim 1, wherein a tool assembly is provided in said front section including two disc-shaped coaxial cutter blades, namely said first cutter blade on a first side of the center plane of the tool carrier and a second cutter blade on the opposite, second side of said center plane, and that any plane defined by the sides of said second cutter blade intersects at least one component included in the rear section of the machine. 